1. Field of the Invention
This invention pertains to an implant for passing blood flow directly between a chamber of the heart and a coronary vessel. More particularly, this invention pertains to an insertion tool to facilitate insertion of such an implant into the coronary vessel.
2. Description of the Prior Art
U.S. Pat. No. 5,755,682 dated May 26, 1998 and PCT Application No. PCT/US97/13980 (International Publication No. WO 98/06356 based U.S. patent application Ser. No. 08/882,397 filed Jun. 25, 1997) teach an implant for defining a blood flow conduit directly from a chamber of the heart to a lumen of a coronary vessel. An embodiment disclosed in the aforementioned patent and applications teaches an L-shaped implant in the form of a rigid conduit. The conduit has one leg sized to be received within a lumen of a coronary artery and a second leg sized to pass through the myocardium and extend into the left ventricle of the heart. As disclosed in the above-referenced patent and applications, the conduit is rigid and remains open for blood flow to pass through the conduit during both systole and diastole. The conduit penetrates into the left ventricle in order to prevent tissue growth and occlusions over an opening of the conduit.
Commonly assigned and co-pending U.S. patent application Ser. No. 08/944,313 filed Oct. 6, 1997, entitled "Transmyocardial Implant" teaches an implant such as that shown in the aforementioned '682 patent with an enhanced fixation structure. The enhanced fixation structure includes a fabric surrounding at least a portion of the conduit to facilitate tissue growth on the exterior of the implant.
Implants such as those shown in the aforementioned applications include a portion to be placed within a coronary vessel and a portion to be placed within the myocardium. When placing a portion of the implant in the coronary vessel, the vessel is axially incised a length sufficient to insert the implant. Such an incision results in a contraction of the coronary vessel to a size substantially smaller than the implant. Therefore, it is difficult to insert the implant into the lumen of the coronary vessel. Such vessels are elastic and can be urged to an expanded shape sufficient to fit over the implant. However, due to the small size of the vessel, restricted space for manipulating surgical tools, and the importance of avoiding damage to the coronary vessel, such a manipulation of the vessel is difficult.